use PDI to end the isolated scope for RLI (#141345)

will fix https://github.com/flutter/flutter/issues/141344

https://unicode.org/reports/tr9/#Explicit_Directional_Isolates
https://api.flutter.dev/flutter/foundation/Unicode/RLI-constant.html

packages/flutter/lib/src/widgets/semantics_debugger.dart

@@ -318,7 +318,7 @@ class _SemanticsDebuggerPainter extends CustomPainter {
       } else {
         switch (data.textDirection!) {
           case TextDirection.rtl:
-            effectivelabel = '${Unicode.RLI}$tooltipAndLabel${Unicode.PDF}';
+            effectivelabel = '${Unicode.RLI}$tooltipAndLabel${Unicode.PDI}';
           case TextDirection.ltr:
             effectivelabel = tooltipAndLabel;
         }

packages/flutter/test/widgets/semantics_debugger_test.dart

@@ -524,6 +524,27 @@ void main() {
     // ignore: avoid_dynamic_calls
     expect(_getSemanticsDebuggerPainter(debuggerKey: debugger, tester: tester).labelStyle, labelStyle);
   });
+
+  testWidgets('SemanticsDebugger label for rtl.', (WidgetTester tester) async {
+    final UniqueKey debugger = UniqueKey();
+    final Key label = UniqueKey();
+
+    await tester.pumpWidget(
+      Directionality(
+        textDirection: TextDirection.rtl,
+        child: SemanticsDebugger(
+          key: debugger,
+          child: Semantics(
+            label: 'ملصق',
+            textDirection: TextDirection.rtl,
+            key: label,
+          ),
+        ),
+      ),
+    );
+
+    expect(_getMessageShownInSemanticsDebugger(widgetKey: label, debuggerKey: debugger, tester: tester), '\u2067ملصق\u2069');
+  });
 }
 
 String _getMessageShownInSemanticsDebugger({